Treatment of pyritic copper and copper-nickel ores.



TREATMENT OF PYBITIC COPPER AND COPPER-NICKEL GEES.

N0 Drawing.

To all whom it may concern:

Be it known that I, JAMES TAYLOR CAR- nioK, geologist, subject of theKing of Great Britain, residing at the New Olub, Johannesburg,Transvaal, have invented new and use' ful Improvements in the Treatmentof Pyritic Copper and Copper-Nickel Ores, of which the following is aspecification.

The present invention is a wet process for the direct treatment of orescontaining copper sulfid and iron with or without nickel; the processbeing applicable to the treatment of ores which on account of their lowgrade or special local conditions will not pay for smelting. The processis superior to other direct processes for the treatment of such lowgrade ores since in the majority of cases it enables practically thewhole of any nickel or cobalt present to be recovered.

Ores containing the higher sulfids of the metals are subjected, prior tothis process, to a preliminary partial desulfurization in the absence ofair in order to render them soluble in acid, the hot desulfurized orebeing dropped into water in order to comminute it. The crushed ore, thusprepared if necessary, or in its raw state where possible, is digestedwith the assistance of heat with an excess of hydrochloric acid, in theabsence of oxygen, untilt-he iron and also the nickel if resent, aredissolved out. The hydrogen sul d evolved by such digestion is convertedinto sulfuric acid, which is used for regenerating the hydrochloricacid, as stated hereunder. The digester liquor is leached or otherwisewithdrawn from the undissolved cuprous residue without allowing air tocome in contact with said residue; and where nickel is present, it isseparated from the iron by suitable steps such as the following. Thesolution is rendered strongly alkaline with ammonia, and air isaspirated through it for a prolonged period. Any nickel carried downwith the iron precipitate so formed is dissolved out of it with dilutehydrochloric acid, which acid is then added to that for a subsequentdigestion. The bulk of the nickel remains in solution, and after removalof the iron precipitate, such nickel is thrown down by the addition oflime. The calcium chlorid solution remaining after removal of the ironand nickel is treated in slight excess, with, for instance, the sulfuricacid manufactured from the hydrogen sulfid evolved during digestion ashereinbefore de- Specification of Letters Patent.

Application filed June 8, 1909.

ltatei'ited Feb. it, 1910. Serial No. 500,899.

scribed. By this means calcium sulfate is precipitated and hydrochloricacid set free; the latter being then distilled off from the calciumsulfate, condensed and employed for the digestion of further ore. Theore reto maining in the treatment vat after removal of the iron andnickel, consists of a porous mass of gangue and cuprous sulfidcontaining some free acid. It is now caused to oxidize; preferably byadding water and 6-5 sulfuric acid and strongly agitating the pulp soformed, by injection of compressed air. Owing to its cellular conditionthe bulk of the sulid rapidly oxidizes to cupric sulfate, which may,after say 24 hours, be leached out. The sulfate of copper may becrystallized out of solution and either marketed as. such or treated asdesired for the recovery of metallic copper. The residue is then thrownout onto a dump which is laid on impervious ground and maintained in anacid condition by sprinkling it with dilute sulfuric acid from time totime as may be necessary. For this purpose the excess acid made from thehydrogen sulfid as herein described may be used. By this means theremaining copper sulfids are converted entirely into soluble sulfate,without the formation of insoluble compounds. The cupric sulfate soformed is gradually leached outby the acid water assisted by any rainwhich may fall, the liquid which percolates from the bottom of the dumpbeing collected in trenches and treated for the recovery of its copper.

What I claim and desire to secure by Letters Patent is:

1. The process of treating pyritic copper ores, which consists inrcn'ioving the iron so as to leave the copper sulfid in a porouscondition, subsequently oxidizing said sul-. fld in the presence of acidand leaching out the sulfate so formed.

2. The process of treating pyritic copper ores, which consists indigesting the crushed ore with hydrochloric acid in the absence of air,until the iron is substantially dissolved and the cuprous sulfid is leftin a porous condition, removing the dissolved iron, subsequently oxidingthe cuprous residue in the presence of acid and leaching out the coppersulfate so formed.

3. The process of treating pyritic copper nickel ores, which consists indigesting the crushed ore with hydrochloric acid in the absence of air,until the iron and nickel are substantially dissolved and the coppersulfid is left in a porous condition, Withdrawing the liquor, removingthe iron and nickel separately therefrom, subsequently oxidizing thecuprous residue in the presence of acid and leaching out the coppersulfate so formed.

4. The process of treating pyritic copper nickel ores, Which consists indigesting the crushed ore with hydrochloric acid in the absence of air,until the iron and nickel are substantially dissolved out and the coppersulfid is left in a porous condition, Withdrawing the liquor,precipitating the iron therefrom by the addition of excess ammonia andoxidation, removing said precipitate, precipitating the nickel by meansof lime, oxidizing the cuprous digester residue in the presence of acidand leaching out the copper sulfate so formed.

The process of treating pyritic copper nickel ores, which consists inremoving the iron so as to leave the copper sulfid in a porouscondition, subsequently oxidizing said sulfid, in the presence of acid,by addition of Water thereto and agitating the pulp so formed With air,leaching out cupric sulfate so formed, conveying the residue to a dump,maintaining said dump in an acid condition and leaching the same.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing Witnesses.

J AMES TAYLOR CARRICK.

\Vitnesses ALFRED L. Sroon, IIILLMAN VINCENT.

